Much of the improved efficiency associated with the X1800 can be attributed to Shader Model 3.0 features such as dynamic flow control, dynamic branching, and high thread counts. Without going into too much technical detail, the upshot is that the shaders in X1800 will only ever process what they absolutely have to, so the amount of wasted cycles is reduced to a minimum. With this in mind, ATI felt that there was no need to increase the number of pixel pipelines from the previous generation.
Parallax Occlusion Mapping employs ATIâ€™s Ultra-Threaded SM 3.0 technology and gives a three dimensional appearance to surfaces. ATI showed this feature off using its Toy Shop demo, which I have to say looked absolutely staggering. You see a lot of great graphic demos from both ATI and nVidia, but this one really was breathtaking. Zooming in on brick wall surfaces and cobble stones, showed a 3D appearance from every angle, adding a touch more realism to the environment. Of course whether POM will be adopted by developers remains to be seen.
ATI has updated its anti-aliasing as well, with adaptive anti-aliasing. ATI claims that adaptive anti-aliasing provides superior image quality without incurring a performance hit over standard multisample anti-aliasing. Unfortunately I havenâ€™t had enough time to play with adaptive anti-aliasing to formulate a definitive opinion, but Iâ€™ll definitely be spending some time with it over the coming weeks and report back.
One feature that ATI understandably wanted to shout about was HDR support with anti-aliasing. Theoretically, this gives you the best of both worlds, with realistic lighting effects, coupled with a smooth environment free from visual aberrations and artefacts. The only problem is that HDR inflicts such a heavy performance hit, that the addition of anti-aliasing on top of it is likely to cripple even the fastest of graphics cards. Of course it give some justification to an X1800 CrossFire system for anyone that doesnâ€™t want a massive CRT on their desk.
Talking of large screens, ATI has equipped the X1800 cards with dual dual-link DVI ports, which means that you could â€“ if you had a lot more money that me â€“ run two 30in Apple Cinema Displays. With each of these screens running at a jaw dropping resolution of 2,560 x 1,600 youâ€™d have more desktop real estate than you could know what to do with.